Long-term Outcome of Keratolimbal
Allograft with or without Penetrating
Keratoplasty for Total Limbal Stem
Cell Deficiency
Abraham Solomon, MD,1 Pierre Ellies, MD,1 David F. Anderson, FRCOphth,1 Amel Touhami, MD,1
Martin Grueterich, MD,1 Edgar M. Espana, MD,1 Seng-Ei Ti, MD,1 Eiki Goto, MD,1 William J. Feuer, MS,1,2
Scheffer C. G. Tseng, MD, PhD1,3
Purpose: To evaluate the long-term outcome of ocular surface reconstruction, including keratolimbal
allograft (KLAL) and amniotic membrane transplantation (AMT) with or without penetrating keratoplasty (PKP), in
patients with nonambulatory vision secondary to total limbal stem cell deficiency (LSCD).
Design: Retrospective, noncomparative interventional case series.
Participants: Thirty-nine eyes in 31 consecutive patients with total LSCD, as defined by impression cytology, who had a preoperative best-corrected visual acuity of less than 20/200 and a minimum follow-up of 12
months. Patients were divided into three groups: group 1 (16 eyes) with chemical burns, group 2 (9 eyes) with
Stevens-Johnson syndrome (SJS), and group 3 (14 eyes) with other causes of LSCD, including ocular cicatricial
pemphigoid, atopic keratoconjunctivitis, and aniridia.
Intervention: All patients underwent KLAL and AMT by one surgeon (SCGT). If needed, PKP was performed
at the same surgical setting using tissue from the same donor.
Main Outcome Measures: Cumulative rates of survival of ambulatory vision (ⱖ 20/200), survival of KLAL,
survival of PKP, and incidence of complications.
Results: Fifty-three KLAL with AMT procedures were performed in 39 eyes, of which 23 eyes received
simultaneous PKP at the time of the first KLAL. The mean follow-up was 34.0 ⫾ 21.5 months (range, 12–117.6).
The mean period of ambulatory vision was 23.9 ⫾ 20.9 months (range, 0 –104). The overall survival of ambulatory
vision was 53.6% at 3 years and 44.6% at 5 years. The survival of ambulatory vision was significantly worse in
SJS compared with other causes (67%, 81%, and 92% for groups 1, 2, and 3, respectively; P ⫽ 0.06 for group
1 versus 2, P ⫽ 0.0008 for group 1 versus 3). KLAL performed alone resulted in higher survival of ambulatory
vision at 2 years (86.1% ⫾ 9.1%) compared with KLAL with PKP (46.9% ⫾ 10.6%, P ⫽ 0.100). The survival of
PKP was significantly worse in SJS compared with the other causes (20.0% ⫾ 17.9% compared with 55.6% ⫾
11.7%, respectively, P ⫽ 0.028). After 2 years, the survival of the second KLAL was better than that of the first:
68.2% ⫾ 15.4% compared with 27.3% ⫾ 13.4%, respectively (P ⫽ 0.041).
Conclusions: Ambulatory vision for a period of more than 2 years can be achieved by KLAL with or without
PKP in eyes with severe ocular surface disorders caused by total LSCD. However, a progressive decline of the
visual outcome and graft survival is evident with time. Performing PKP simultaneously with KLAL may be
associated with a less favorable outcome. The failure of KLAL is associated with the loss of donor cells in the
recipient. Augmentation of ocular surface defense is essential in securing the success of KLAL and PKP. Future
modifications of the surgical procedure and of the immune suppressive protocols may improve survival of the
allogeneic grafts and the final visual outcome. Ophthalmology 2002;109:1159 –1166 © 2002 by the American
Academy of Ophthalmology.
Originally received: June 27, 2001.
Accepted: August 28, 2001.
Manuscript no. 210446.
1
Department of Ophthalmology, Bascom Palmer Eye Institute, Miami,
Florida.
2
Department of Biostatistics, Bascom Palmer Eye Institute, Miami, Florida.
3
Department of Cell Biology & Anatomy, University of Miami School of
Medicine, Miami, Florida.
Supported in part by an unrestricted grant from Research to Prevent
© 2002 by the American Academy of Ophthalmology
Published by Elsevier Science Inc.
Blindness, Inc., New York, New York, la Banque Française des yeux,
Paris, France (PE), the T.F.C. Frost Charitable Trust, London, England
(DFA), and the Deutsche Forschungsgemeinschaft, Bonn, Germany (MG)
(GR1814/1-1).
SCGT has obtained a patent on preparation and clinical uses of the
amniotic membrane.
Reprint requests to Scheffer C. G. Tseng, MD, PhD, Ocular Surface
Center, 8780 SW 92 Street, Suite 203, Miami, FL 33176.
ISSN 0161-6420/02/$–see front matter
PII S0161-6420(02)00960-0
1159
Ophthalmology Volume 109, Number 6, June 2002
Stem cells of the corneal epithelium are located at the
limbus1 and are ultimately responsible for renewal and
regeneration of the entire corneal epithelium under normal circumstances and during wound healing.2,3 Diseases
causing either a complete loss of limbal epithelial stem
cells or severe destruction of the limbal stroma result in
the pathologic state of total limbal stem cell deficiency
(LSCD).4 Patients with total LSCD invariably complain
of pain and photophobia and have severe loss of vision
caused by the invading vascularized conjunctiva. Because the life span of corneal epithelial progenitor cells
from a corneal graft is limited, total LSCD cannot be
treated by penetrating keratoplasty (PKP) alone, and visual rehabilitation depends on transplantation of limbal
epithelial stem cells.5,6
When total LSCD involves only one eye, successful
reconstruction can be achieved by transplanting autologous
limbal epithelial stem cells from the fellow eye in a procedure termed “limbal conjunctival autograft.”7–11 However,
when total LSCD involves both eyes, corneal surface reconstruction relies on transplantation of an allogeneic
source of limbal epithelial stem cells. This can be achieved
by limbal conjunctival allograft from living-related donors12,13 or keratolimbal allograft (KLAL) from cadaveric
donors.12,14 –16 Because the source of limbal epithelial stem
cells is allogeneic, the survival of the graft depends on
systemic immunosuppression. Despite the continuous administration of systemic cyclosporin A, the success rate of
KLAL declines from 75% to 80%14 –16 after 1 year to 50%17
after 3 years of follow-up. This finding strongly suggests
that there are unknown clinical variables that affect the
outcome of KLAL, and underscores the importance of
identifying and measuring these variables in a long-term
study.
A major variable that may complicate the outcome analysis of KLAL is additional PKP that is needed to restore
corneal transparency when LSCD is accompanied by deep
corneal scarring.12,17–20 The conventional method of grouping KLAL failure and PKP failure together as a single end
point analysis may not disclose the true survival of KLAL
or PKP. Other important variables include the heterogeneous nature of the underlying cause, the varying degrees of
LSCD severity, and different extents of dysfunctional external adnexae, which may independently affect the outcome of KLAL.
In an attempt to address these potential variables, we
present herein the long-term outcome of KLAL in patients
with nonambulatory vision secondary to total LSCD by
evaluating the survival of KLAL and PKP separately and
according to the underlying ocular surface disease. Furthermore, the visual outcome is measured not by mean preoperative and final visual acuity, as previously reported,12,17–20 but by the period of ambulatory vision achieved
in a manner similar to that reported by Dohlman and
Terada21 for evaluating the visual outcome in the use of
keratoprosthesis. The contribution of other variables relating to the dysfunctional ocular surface defenses in affecting
such outcome is analyzed as well.
1160
Materials and Methods
Patients
This study was approved by the Medical Science Subcommittee
for the Protection of Human Subjects in Research of the University
of Miami School of Medicine, Miami, Florida. Each patient gave
written informed consent after explanation of the nature, risks, and
possible adverse consequences of the procedure. One surgeon
(SCGT) performed all surgeries at one center (i.e., the Bascom
Palmer Eye Institute). The entry criteria for the study were patients
with total LSCD who underwent KLAL and amniotic membrane
transplantation (AMT), had a best-corrected visual acuity (BCVA)
of less than 20/200, and had been followed up for at least 12
months postoperatively. On the basis of these criteria, 53 KLAL
procedures were performed on 39 eyes of 31 patients (21 males, 10
females) between January 1991 and January 1999. The last follow-up visits for all patients, for the purpose of data analysis, took
place between January and April 2001.
Diagnosis of LSCD was made clinically and was confirmed in
28 of 39 eyes by impression cytology showing goblet cells on the
corneal surface, as previously reported.18,22 In the remaining 11
eyes, the diagnosis of LSCD was clinically evident as shown by
late fluorescein staining, loss of limbal palisade of Vogt, superficial vascularization, signs of complete conjunctivalization, or keratinization of the cornea, and impression cytology was thus not
considered necessary. These 39 eyes were further divided into
three groups according to the underlying causes. Group 1 included
patients with chemical burns (16 eyes), group 2 had patients with
Stevens-Johnson syndrome (9 eyes), and group 3 included all other
causes such as ocular cicatricial pemphigoid (2 eyes), atopic keratoconjunctivitis (3 eyes), contact lens-induced keratopathy (2
eyes), herpes simplex virus keratitis (1 eye), multiple surgeries (1
eye), aniridia (1 eye), and idiopathic causes (4 eyes). Data were
gathered by retrospective review of the medical and operative
records. Previous surgeries before referral to Bascom Palmer Eye
Institute were also considered and included PKP, KLAL, anterior
segment reconstruction, lid surgery, and glaucoma surgery. Other
procedures performed during this study were recorded and included punctal occlusion, filtering surgery, lid reconstruction, and
tarsorrhaphy to restore the healthy ocular surface defense.
Transplantation of Limbal Epithelial Stem Cells
All surgeries were performed with the patient under local anesthesia. Transplantation of allogeneic limbal epithelial stem cells by
means of KLAL was performed as previously described.18 Scarred
and inflamed tissue was removed by superficial keratectomy in the
entire limbal and corneal surfaces. Amniotic membrane provided
by Bio-Tissue (Miami, FL) was used as a graft to reduce inflammation and scarring in the underlying stroma and to prepare the
stromal bed for stem cell transplantation. For all cases, a 360°
corneolimbal ring graft was prepared from a remaining corneoscleral ring after a conventional 8.0-mm trephination of a cadaveric donor button stored in a modified MK medium without human
leukocyte antigen matching. This donor corneolimbal ring was
thinned from the endothelial aspect by dissection with sharp Westcott scissors. It was then secured to the surrounding conjunctival
edge with 9-0 or 10-0 interrupted Vicryl sutures with episcleral
bites and, if necessary, to the denuded corneal surface with a
running 10-0 nylon suture. When PKP was needed, it would be
performed first and immediately followed by KLAL at the same
surgical setting using the same donor. The central corneal donor
button was first secured to the host tissue with eight interrupted
10-0 nylon sutures. The donor corneolimbal rim was then transferred to the recipient eye to fit exactly with the outside border of
Solomon et al 䡠 Keratolimbal Allografts for Stem Cell Deficiency
the secured central corneal button. The KLAL was then secured to
the surrounding conjunctival edge in the same manner as that
described previously and to the donor corneal button using a
second set of eight interrupted 10-0 nylon sutures, which were
passed to include portions of donor corneal button, recipient peripheral cornea, and donor ring graft. Maxitrol (neomycin, polymyxin B, and dexamethasone) ointment (Alcon Laboratories, Inc.,
Fort Worth, TX) was applied at the end of the procedure.
Postoperatively, all patients received nonpreserved 1% methylprednisolone eye drops (Bascom Palmer Eye Institute Pharmacy)
every 2 hours while awake and 0.3% ofloxacin (Allergan, Irvine,
CA) three times a day, of which the former was tapered to a
maintenance dose over 1 month and the latter was discontinued
when epithelialization was completed. Sutures were removed at 3
to 6 weeks. All patients received oral cyclosporin A at a dosage of
5 mg/kg body weight a day in divided doses starting at 1 week
before or at the time of KLAL. Cyclosporin A was then tapered to
1 to 2 mg/kg in 4 to 8 weeks, so that the trough blood level was
maintained at 100 to 150 ng/ml, and administered indefinitely.
Renal and liver function tests were monitored at appropriate intervals. Patients with aqueous tear deficiency were treated with
preservative-free Refresh Plus (Allergan, Irvine, CA) lubricants or
autologous serum drops. Punctal occlusion by cauterization had
been performed in both upper and lower lids if there was severe
aqueous tear deficiency or a neurotrophic state as diagnosed by the
Cochet-Bonnet esthesiometer (Luneau, Paris, France).23
Clinical Evaluation of Main Outcome Measures
Maintenance of Ambulatory Visual Acuity. The BCVA was
measured at each clinical visit. Nonambulatory vision was defined
as a BCVA ⬍ 20/200, whereas ambulatory vision was defined as
a BCVA ⱖ 20/200. For each eye the postoperative time period
during which ambulatory vision was continuously maintained was
recorded, following a method described by Dohlman and Terada21
for the postoperative evaluation in patients with keratoprosthesis.
When the BCVA deteriorated to the level below the cut-off point
of 20/200, the eye was considered as a failure for the purpose of
survival analysis.
Survival of KLAL. Survival of transplanted limbal epithelial
stem cells was defined by the duration of maintaining a normal
corneal epithelial phenotype after surgery. Failure of the KLAL
and subsequent recurrent LSCD was defined as the appearance of
diffuse late fluorescein staining, conjunctivalization, vascularization of the cornea through the limbus, or persistent epithelial
defects with diffuse persistent irregular epithelium after correction
of lid malposition, trichiasis, symblepharon, and dry eye. In addition to slit-lamp examination, impression cytology was performed
when necessary to confirm the presence of conjunctival goblet
cells on the corneal surface. Failure of KLAL was also diagnosed
when there were clear signs of rejection (congestion of the perilimbal and limbal blood vessels and swelling of the tissue, as
previously described),14 but was also diagnosed in cases in which
rejection could not be detected.
Survival of the Central Corneal Graft (PKP). Survival of
corneal allograft was defined conventionally by maintenance of a
clear and compact corneal tissue that allowed a clear view of
underlying iris detail. Corneal allograft failure was diagnosed by
classic signs of endothelial or epithelial rejection lines and subepithelial infiltrates, keratic precipitates, stromal edema, and corneal
opacification.
Complications
All postoperative complications were carefully recorded. Raised
intraocular pressure was considered a complication when glau-
coma had not been diagnosed before surgery. Corneal epithelial
defects were considered to be persistent when they were observed
for more than 2 weeks. Persistent epithelial defects were treated by
artificial tear supplementation, punctual occlusion, autologous serum drops, lid reconstruction, amniotic membrane transplantation,
and tarsorrhaphy. When persistent epithelial defects remained despite these treatments, they were considered a complication.
Statistical Analysis
The data were analyzed with the assistance of the Biostatistics
Department at Bascom Palmer Eye Institute. Kaplan-Meier survival analysis was performed to evaluate three outcome measures:
the cumulative incidence of maintaining ambulatory vision, KLAL
survival, and PKP survival. The effect of several clinical parameters (such as cause, concomitant PKP, first versus second procedure, preoperative procedures, lid surgery during the follow-up
period, symblepharon, and postoperative secondary glaucoma) on
the survival of the three outcome measures was evaluated by
univariate survival analysis and by Cox proportional hazards survival regression. The log-rank test was used to compare univariate
survival curves. SPSS version 7.5 (SPSS Inc., Chicago, IL) was
used for data analysis.
Results
Fifty-three KLAL procedures were performed on 39 eyes of 31
patients. The mean age of the patients was 40.1 ⫾ 14.6 years. The
mean follow-up period was 34.0 ⫾ 21.5 months (range, 12–117.6).
Twenty-eight of 39 eyes (74.4%) underwent one KLAL transplantation, 9 eyes had two KLAL procedures, one eye had 3, and
another eye had 4 KLAL procedures (Table 1). Twenty-four eyes
underwent a total of 45 PKP procedures. The first PKP procedure
was performed simultaneously with a KLAL procedure, using the
same donor. Twelve of 24 eyes (50.0%) underwent one PKP, and
11 eyes had 2 to 4 PKPs. Table 1 shows the number of surgical
procedures according to the cause of LSCD.
Survival of Ambulatory Vision
The overall mean period of ambulatory vision was 23.9 ⫾ 20.9
months (range, 0 –104 months). Eyes that sustained chemical burns
(group 1) had ambulatory vision for a mean period of 32.4 ⫾ 27.9
months, whereas eyes with Stevens-Johnson syndrome (SJS) and
other causes (groups 2 and 3) had considerably shorter mean
ambulatory vision periods of 15.2 ⫾ 12.4 months and 19.9 ⫾ 11.5
months, respectively (Fig 1A). The mean period of ambulatory
vision for eyes with SJS was significantly shorter than that for eyes
with chemical burns (P ⫽ 0.046).
Survival analysis of the overall change of ambulatory vision
with time showed a progressive decline of the cumulative proportion of eyes enjoying BCVA of 20/200 or better (Fig 1B). After 1
year of follow-up, 76.6% ⫾ 6.8% of eyes had ambulatory vision.
This proportion further declined to 53.6% ⫾ 9.9% at 3 years, and
to 44.6% ⫾ 11.6% at 5 years.
The cause of limbal deficiency was found to have a significant
effect on the final visual outcome. SJS had the lowest cumulative
proportion of eyes with ambulatory vision after 2 years of follow-up compared with the other two groups (Fig 1C): 29.6% ⫾
16.4% (SJS) compared with 62.5% ⫾ 1.2% (chemical burn, P ⫽
0.067) and 92.3% ⫾ 7.4% (others, P ⫽ 0.00008).
Performing PKP concomitantly with KLAL, during the first
KLAL procedure, was found to decrease the visual outcome compared with performing KLAL alone (Fig 1D). Only 46.9% ⫾
1161
Ophthalmology Volume 109, Number 6, June 2002
Table 1. Number of Eyes and of Surgical Procedures (Keratolimbal Allograft and Penetrating Keratoplasty) According to the Three
Etiology Groups
Procedures
Total eyes with KLAL
Eyes with 1 KLAL
Eyes with 2 KLAL
Eyes with 3 KLAL
Eyes with 4 KLAL
Total KLAL procedures
Total eyes with additional PKP
Eyes with 1 PKP
Eyes with 2 PKP
Eyes with 3 PKP
Eyes with 4 PKP
Total PKP procedures
Group 1:
Chemical
Burns
16
11
4
1
23
15
8
3
1
3
29
Group 2:
StevensJohnson
Syndrome
Group 3:
Other
Causes
9
7
1
1
14
10
4
12
5
2
1
2
18
4
2
2
10
6
Total
39
28
9
1
1
53
24
12
6
3
3
45
KLAL ⫽ keratolimbal allograft; PKP ⫽ penetrating keratoplasty.
10.6% of eyes that had undergone KLAL and PKP had ambulatory
vision at 2 years compared with 86.1% ⫾ 9.1% for eyes that had
KLAL alone (P ⫽ 0.10). However, after 3 years, no difference in
ambulatory vision survival was noted between eyes that had simultaneous KLAL and PKP (43.1% ⫾ 30.8%) and eyes that had
KLAL alone (39.1% ⫾ 11.4%).
Cox proportional hazard survival regression analysis revealed
that the most significant variables associated with reduced survival
of the ambulatory vision were SJS (P ⫽ 0.047), younger age (P ⫽
0.041), and performing PKP simultaneously with KLAL (P ⫽
0.058). Other variables such as preoperative glaucoma, the number
of previous surgical procedures, the presence of symblepharon, or
lid surgery performed during the follow-up period did not have an
effect on the visual outcome in the multivariate regression analysis.
Survival of KLAL
A progressive attrition in the survival of KLAL was noted during
more than 5 years of follow-up (Fig 2A). The survival of KLAL
was 76.9% ⫾ 6.7% at 1 year, 47.4% ⫾ 11.7% at 3 years, and only
23.7% ⫾ 17.7% at 5 years. This trend seemed to parallel the
decline of ambulatory vision over the follow-up period.
No differences in KLAL survival were noted between the three
groups (Fig 2B). Univariate analysis did not demonstrate any
effect for the number of previous procedures, previous glaucoma,
presence of symblepharon, or lid surgery on KLAL survival.
Although not significantly different, performing PKP with KLAL
at the same session was associated with a markedly reduced KLAL
survival after 2 years (Fig 2C, 81.2% ⫾ 9.8% when KLAL was
performed alone compared with 58.9% ⫾ 10.6% when KLAL was
performed with PKP, a decrease of 27.5%; P ⫽ 0.17).
In 11 eyes, a second KLAL was performed after failure of the
first KLAL. Comparison of the survival curves of the second with
the first KLAL in these 11 eyes demonstrated a significantly higher
survival for the second graft (Fig 2D). The survival of the second
KLAL after 2 years was 68.2% ⫾ 15.4% compared with 27.3% ⫾
13.4% for the first KLAL (P ⫽ 0.041).
Survival of PKP
An overall progressive decline in central corneal graft survival was
observed from 47.8% ⫾ 10.4% after the first year to 13.7% ⫾
1162
8.4% after 3 years (Fig 3A). As in KLAL, eyes with SJS had a
significantly shorter survival compared with the other two groups
(Fig 3B). After 1 year, the cumulative survival of eyes with SJS
was 20.0% ⫾ 17.9% compared with 55.6% ⫾ 11.7% for the other
two groups, whereas after 2 years of follow-up, none of the SJS
central grafts had survived compared with 42.3% ⫾ 12.1% in the
other groups (P ⫽ 0.028).
Univariate survival analysis demonstrated a significant effect
for the need to perform a lid surgery during the follow-up period.
In eyes that required lid surgery to correct entropion, lid margin
keratinization, or exposure, a significantly shorter survival of the
central corneal graft was demonstrated compared with eyes in
which no such surgery was needed (P ⫽ 0.034) (Fig 3C). Other
parameters such as previous surgical procedures, previous glaucoma, and presence of symblepharon were not found to have an
effect on central corneal graft survival. In addition, no difference
was found between the survival of the first PKP compared with the
second PKP in the 12 eyes that had undergone more than one PKP
(Fig 3D).
Complications
Ten of 39 eyes (25.6%) developed elevated intraocular pressure
after surgery. Eight of these 10 eyes (80.0%) had undergone one to
three PKPs, which is a known risk factor for developing an
elevated pressure. Nine of the 10 eyes required a glaucoma filtering procedure (a Baerveldt implant) to control the intraocular
pressure.
Fourteen eyes (35.9%) developed persistent epithelial defects.
All defects except one healed by punctual occlusion (8 eyes), lid
surgeries (10 eyes), and an amniotic membrane transplantation as
a patch (9 eyes). The only one eye with refractory persistent
epithelial defect as a complication had SJS with severe dry eye.
Three eyes developed microbial keratitis. Two corneal grafts
were severely infected by Candida species, which led to a central
corneal graft failure and to a repeat penetrating keratoplasty. Both
of these two infected grafts were also associated with secondary
severe tractional retinal detachment. One eye infection had coagulase negative Staphylococcus in a loose suture, which was successfully treated with topical 0.3% ofloxacin.
One eye with successful corneal surface reconstruction developed postoperative cystoid macular edema. Three eyes with severe
chemical burns developed tractional retinal detachment as a result
Figure 1. Analysis of the survival of ambulatory vision. A, Mean time periods of maintaining ambulatory vision in the three etiology groups. B,
Kaplan-Meier survival curve of ambulatory vision in all 39 eyes. A progressive decline is evident with time. C, Survival of ambulatory vision according
to different causes. Eyes with Stevens-Johnson syndrome had a significantly lower survival of ambulatory vision compared with the other two groups. D,
Survival of ambulatory vision according to the inclusion of penetrating keratoplasty (PKP) with the first keratolimbal allograft (KLAL). Performing KLAL
with PKP was associated with reduced survival of ambulatory vision during the first 2 years. Tables show cumulative percentages ⫾ standard deviation
of eyes that maintained ambulatory vision.
Figure 2. Analysis of variables affecting the survival of keratolimbal allograft (KLAL). A, Kaplan-Meier survival curve of KLAL in all 39 eyes. A
progressive decline is evident with time. B, No differences were found between the effects of different causes on KLAL survival. C, Survival of KLAL
according to the inclusion of penetrating keratoplasty (PKP) with the first KLAL. Performing KLAL with PKP was associated with a marked, although
not significant, reduction in KLAL survival. D, Survival of the second KLAL was found to be significantly better than that of the first KLAL. Tables show
cumulative percentages ⫾ standard deviation of eyes that had KLAL survival.
Ophthalmology Volume 109, Number 6, June 2002
of deep penetration of the chemical into the posterior pole, leading
to vitreitis and proliferative vitreoretinopathy.
Discussion
Reconstruction of the ocular surface in eyes with severe
LSCD remains one of the most challenging problems in
ophthalmology. It takes a set of preoperative measures to
prepare the ocular surface defense mechanisms for surgery,
requires demanding surgical procedures of KLAL and AMT
with or without PKP, and involves a prolonged postoperative management that includes immunosuppression and
continuous care for the maintenance of the ocular surface
health (for reviews see references 2, 3, 5, and 12). Because
this field is still evolving, little is known about the long-term
outcome of these patients. Except for the recent study by
Tsubota et al,17 there have been only a few reports on a
relatively small number of patients with limited followup.13,14,16,19,20,24
In this study we present the long-term outcome of eyes
with total LSCD, for whom a mean follow-up of 34 months
was available, extending in some cases to 5 years. Using
three objective measures to characterize the functional and
anatomic outcome, namely the period of ambulatory vision,
KLAL survival, and PKP survival, we demonstrated an
overall trend of progressive decline of vision and attrition of
these two allografts. Survival analysis demonstrated that
53.6% and 44.6% of eyes maintained visual acuity equal to
or better than 20/200 after 3 and 5 years, respectively. The
cumulative percentage of graft survival 3 years after surgery
was 47.4% for KLAL and 13.7% for PKP.
Of the three outcome measures, the main factor that
might determine the final outcome of these eyes is probably
KLAL survival, because failure of the transplanted limbal
stem cells to survive will invariably result in invasion of
conjunctival epithelium and blood vessels into the central
corneal graft, thereby impairing its clarity. The prognosis
for a successful KLAL may thus be strongly influenced by
preoperative conditions such as tear function and functional
external ocular adnexae. Postoperatively, attrition of KLAL
survival is probably related to persistent inflammation, severe dry eye, or asymptomatic and progressive rejection of
the KLAL. Shimazaki et al25 have recently reported that tear
function affected surgical outcome of KLAL and amniotic
membrane transplantation in patients with SJS. Previous
reports with a shorter follow-up of 1 or 2 years revealed
more favorable results of 70% to 80% success,12,15,16,18,24 a
finding that was also noted in our data for the first 2 years
of follow-up. Rao et al26 have also recently noticed gradual
peripheral vascularization in seven of nine eyes, graft rejection in three eyes, and ambulatory vision in only two eyes
after a short follow-up of 17 months. In Holland’s series,12
Figure 3. Analysis of variables affecting the survival of penetrating keratoplasty (PKP). A, Kaplan-Meier survival curve of 24 eyes that had PKP
with the first keratolimbal allograft (KLAL) procedure. A progressive
decline is evident with time. B, Stevens-Johnson syndrome had a signif-
1164
Š
icantly lower PKP survival compared with the other causes. C, eyes that
required lid surgery had a better PKP survival compared with eyes in which
lid surgery was not performed. D, No differences were found between the
survival of the first and the second PKP.
Solomon et al 䡠 Keratolimbal Allografts for Stem Cell Deficiency
72% of eyes had a stable ocular surface, and 60% had a
significant improvement in visual acuity. In our previous
report,18 we observed corneal graft rejection in 9 of 14
(64%) eyes and limbal allograft rejection in 3 of 21 eyes
(14%). The fact that the success rate declines with time, a
finding consistent with that reported by Tsubota et al,17
further underscores the importance of long-term follow-up
in the investigation of a graft survival.
Recent laboratory data provide conflicting evidence concerning the survival of transplanted limbal epithelial stem
cells in patients receiving KLAL. Using primers that detect
variable nucleotide tandem repeats, the genotype of surface
epithelial cells from recipients of KLAL was compared with
that of scleral samples from remnant donor eyes.27 The
authors noted that in none of the eyes examined were donor
cells recovered from the recipient’s surface 3 to 5 years after
KLAL. A recent immunohistologic study of specimens
from corneas after KLAL rejection could not demonstrate
any epithelium with a corneal phenotype.28 In a rabbit study
of KLAL, none of the recipient corneas regained a normal
corneal surface within the first 5 months after surgery.29 On
the contrary, Shimazaki et al30 detected donor-derived epithelial cells in the paracentral cornea of eyes after KLAL
using fluorescein in situ hybridization probes and restriction
fragment length polymorphism analysis. We suspect that
the failure of KLAL is associated with the loss of donor
cells in the recipient. Further studies comparing the genotyping of donor and recipient epithelial cells in KLAL
transplanted eyes at different time points after the surgery
are needed to evaluate the true survival of donor-derived
cells with time.
In this study, eyes with SJS were found to have the least
favorable visual outcome (29.6% survival of ambulatory
vision at 2 years) and the lowest survival of the central
corneal graft (no surviving grafts at 2 years). SJS is characterized by persistent inflammation coupled with progressive fibrosis, leading to tear film abnormalities and lid
malposition, all of which contribute to progressive attrition
of corneal epithelial cells and progressive exhaustion of the
stem cell population. By use of a similar surgical approach,
a successful outcome of ocular surface reconstruction was
recorded in 13 of 29 (44.8%) eyes in adult patients with
SJS25 and in 2 of 4 children.20 However, the success in these
series was determined by sustained coverage of the corneal
surface by the corneal epithelium, whereas only 9 of 29
(31.0%) eyes achieved a postoperative visual acuity equal to
or better than 20/200.25
When PKP was performed at the same session with
KLAL, we noted a marked reduction in the ambulatory
vision during the first 2 postoperative years, along with a
marked reduction in KLAL survival. Moreover, a progressive decline of PKP survival with time was evident, to the
point at which none of the grafts survived after 5 years
follow-up. Likewise, Shimazaki et al31 reported that 16 of
45 (35.6%) eyes receiving simultaneous PKP and KLAL
developed an endothelial rejection of the central corneal
graft and that, subsequently, 10 of these 16 eyes developed
endothelial decompensation. The poor prognosis of central
corneal graft survival may be partially explained by the
increased exposure of the host immune system to the donor
corneal antigens through the recognition of limbal allograft
antigens, which come from the same donor as the central
corneal graft. Moreover, the addition of PKP at the same
setting might have increased the wound healing response
and inflammation, which are deleterious to stem cell health.
For these reasons, some physicians have advocated waiting
for at least 3 months after KLAL before performing PKP.32
We have since modified our surgical strategy and adopted a
two-step approach by performing KLAL first, followed by a
PKP 3 to 6 months later.
Interestingly, the second KLAL survival rate was 2.5fold greater than that of the first KLAL. Although no data
are yet available on the longevity of repeat KLAL, our
observation contradicts the conventional knowledge on the
survival of corneal regrafts, in which the survival of repeated PKP significantly decreases with the increasing number of regrafting procedures.33 We speculate that postoperative measures to improve the ocular surface defense may
have facilitated a better prognosis for the second KLAL.
Furthermore, both the surgeon’s learning curve in KLAL
and performing the second KLAL without a simultaneous
PKP may have also increased the survival of second KLAL.
Systemic cyclosporin A was used for immunosuppression throughout the study period. Systemic immunosuppression is probably needed for an indefinite time when the
transplanted tissue is allogeneic. Because the rate of graft
survival seemed to be unacceptably low, we have decided to
modify our protocol to include systemic corticosteroids and
mycophenolate mofetil (CellCept, Hoffmann La Roche,
Nutley, NJ), starting 1 month before surgery and tapering
down the corticosteroids during the first postoperative
months while adjusting cyclosporin A and mycophenolate
dosages to a level that can be tolerated by the patient.
Although long-term data are not available, our preliminary
impression is that this modified protocol might improve the
overall success, because the graft tissues and the eyes seem
to be more quiescent.
Ocular surface reconstruction for severe diseases such as
SJS, ocular cicatricial pemphigoid, and chemical burns continues to be one of the most challenging fields in ophthalmology. Our study provides new information regarding the
long-term survival of vision and transplanted tissue in this
set of complicated cases. On the basis of the results of this
study, we have considerably modified our surgical technique and postoperative management. We no longer perform PKP at the same session with KLAL, and prefer to
wait at least 3 months or until the surface inflammation is
diminished. We use the amniotic membrane in all of our
KLAL procedures, first as a graft on which the corneoscleral
rim is sutured and then as a patch over the surface at the end
of the procedure. We emphasize the need for indefinite
immunosuppression in all of our patients after allogeneic
transplants while meticulously monitoring any possible side
effects. Because the overall success rate of such ocular
surface reconstruction remains low, we continue our search
for other strategies. Performing KLAL with tissue from
human leukocyte antigen-matched live related donors may
improve the longevity of KLAL.13,26 The ability to expand
the limbal epithelial stem cells in an ex-vivo environment
1165
Ophthalmology Volume 109, Number 6, June 2002
on the amniotic membrane as a carrier34 –36 may prove to be
an alternative to the current KLAL procedure. Tissue engineering that includes an artificial stroma made from synthetic polymers, with or without epithelial and endothelial
cells, may prove to be another future avenue for surface
reconstruction.37 Keratoprosthesis is yet another alternative
for patients in whom the ocular surface is severely keratinized and dry, and the chances for graft failure are high.21
Some or all of these alternatives may be available in the
future for patients with ocular surface diseases, and we may
be able to choose or tailor the appropriate treatment for each
of our patients according to the underlying disease and the
severity of deficiency in ocular surface defense and LSCD.
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